Impulse transmitting device



March 17, 1942. c. c. PUCKETTE IMPULSE TRANSMITTING DEVICE Filed Aug.14, 1939 4 TTORNEY Patented Mar. 17, 1942 IMPULSE TRANSMITTING DEVICECharles Clarke Puckette, Coventry, England, as,- signor to The GeneralElectric Company Limited, Coventry, England, a British companyApplication August 14, 1939, Serial No. 289,949 In Great Britain August27, 1938 10 Claims.

The invention relates to impulse sending devices of the type provided ontelephone subscribers instruments and operates by rotating a disc by afinger or the like, and the invention has for its object the provisionof improvements in connection with the impulse producing portions of themechanism.

As is well known, in impulse senders of the type referred to above, theimpulses are sent out during the return motion of the finger plate tonormal, each impulse train being preceded by a period correspondingapproximately to the length of two complete impulses. This i known asthe lost motion period, and is for the purpose of providing time forcertain switching operations to be performed at the exchange.

According to the invention, an impulse sender of the type used intelephone systems comprises a toothed impulse sending wheel connected toa finger plate, and acting upon a rocking member rotatable on a pivotwhich is itself guided so as to move substantially radially relativelyto the impulse wheel, the said rocking member acting upon impulseproducing contacts during the return motion only of the finger plate tonormal.

According to a feature of the invention, the toothed wheel is providedWith a felt washer of a diameter slightly greater than that of the rootcircle of the impulse producing teeth, this washer being fixed to theWheel and containing 1ubricant for the impulse producing rocker.

According to another feature of the invention, dust is excluded from.the inside of the mechanism by providing one: or more. discs ofmaterial. such as synthetic resin, these discs being an accurate fit onthe shaft carrying the finger plate, and being placed between two ormore further discs of similar material fixed to the finger plate itself,each of the latter discs having a hole considerably larger than the saidshaft.

In, an embodiment of the invention, the impulse sending device isprovided with a toothed impulse producing wheel fixed to a shaftcarrying the finger plate. The teeth of this wheel act upon a spur of arocking member during the wind-up motion of the sender, rotating thesaid member on a pivot which is fixed to an arm. This arm is pivoted atits other end to the frame of the sender, and is rotated through anangle in order to allow the spur and rocking member to be rotated to alimited degree by the teeth of the impulse producing wheel at thecommencement of the wind-up period.

When the return motion commences, the rockdirection through thepreviously stated degree of motion, thus providing the lost motionperiod required. At the end of this period the spur is lifted anddropped alternatively by the teeth, an insulating collar on the spuropening and closing impulse producing springs carried by the frame ofthe sender.

As an alternative to the foregoing, the pivot of the rocking member maybe carried by a fiat spring tensioned so as to hold the member incontact with the wheel, a tongue of the spring being adopted to retainthe rocking member in either of its extreme positions.

A washer of felt or similar porous material is fixed by means of aspringy disc to the toothed wheel and is provided with a quantity of oilby which the impulse producing members are lubricated. This materialalso acts as a sound deadener.

A dust sealing washer of the type already described is provided inconnection with the shaft of the device,,the, object beingv to permit acertain amount of adjustment to the number plate of the dial duringassembly, relative to the central shaft, without causing gaps to appeararound ing member is carried by the teeth. in. a backward the shaftthrough which dust could obtain access to the interior of the impulsesender.

In order that the nature of the invention may be more particularlydescribed, reference should i be made to the accompanying drawing inwhich Figure 1 is a rear view of an impulse sending device or dial asused by telephone subscribers,

Figure 2 is a section of the device, and Figures 3 and 4 show theimpulse producing portion of the dial. in particular positions to bedescribed later, and Figure 5 is an enlarged view of one form of therocking member.

Referring to Figures 1 and 2, it will be seen that the impulse sendercomprises a toothed impulse producing wheel I, mounted on a shaft 2,this shaft being rotated by the subscriber by means of a finger plate 3,in normal manner. The shaft bears a sprocket wheel 5, which drives afurther gear (not shown) engaging with the worm 4 which is. mounted. onthe same shaft as the fiy-weights 6, formingpart of a normal type ofgovernor mechanism. The shaft 2 also carries an arm. I which engages ina normal position with the contact springs l0, these performingoff-normal circuit functions when the dial is wound up.

The toothed wheel I engages with the spur 4! of a rocking member II whenthe Wheel is rotated, this rocking member being pivoted at l 3 on the;arm 12, this arm itself being pivoted at M so as to have a limiteddegree of rotation. When the dial is rotated in a winding up direction,the first tooth I of the wheel I engages the spur of the rocking memberI I, turning it to the position shown on Figure 3. The spur of themember H is merely a continuation of the pin I6, which carries aninsulating collar I8, the purpose of which will be explained later. Asthe winding up action progresses, the spur is alternately lifted anddropped between the teeth of the wheel I, the arm I2 remaining in theposition shown in Figure 3 whilst the rocking member II pivots about thepoint I3, the said member being returned to the bottom of the teeth eachtime by the fiat spring 20 the front end or tongue of which passes overa cam shaped face of member II.

The extent of movement of the arm I2 is controlled by the engagement ofa projection on it with the slot 40, the projection normally resting onthe end of the slot nearest the centre of the dial. The arm and.projection only leave this position during the initial movement of therocking member from the position shown in Figure 1 to that shown inFigure 3 at the commencement of the winding-up period, and also duringthe initial part of the reverse movement of the dial, prior to impulsesending.

At the end of the wind-up period, the spur of the rocking member IIrests in a space between two teeth of the wheel I. As the return motionof the dial commences, a tooth catches the spur, and rotates the rockingmember II through a considerable angle to approximately the positionshown in Figure 4, the radial movement of the pivoted end of the rockingmember being permitted by the rotation of the arm I2 about its pivot I4.At the end of a period of rotary motion equal to approximately two toothspaces, the arm I2 once more reaches the extent of its travel inwards,and a slight further movement of the wheel I in a return directioncauses engagement of a tooth of the wheel with the spur 4|, lifting theend of rocking member to the position shown in Figure 4. Here the collarI8 engages with one spring of the contact set 22, opening the contactswhile the tooth 23 passes underneath the spur. After the tooth haspassed, the springs 20 and 22 cause the spur to drop into the spacebetween the teeth, with the result that the impulse springs 22 reclose.

Thus an impulse has been sent, the length of which, and the spacingbetween it and successive impulses, is determined by the shape anddimensions ofthe teeth of the wheel I. In addition, a period of lostmotion has been provided at the commencement of the impulse train, thisperiod being prefixed to any digit dialled by the subscriber.

As an alternative to this construction, the pivot I3 may be carried by aflat spring similar to 20, tensioned so as to hold the rocking member incontact with the impulse producing wheel, a tongue of the spring beingadapted to retain the rocking member in either of its extreme positionsin a manner similar to that described in connection with the cam shapedface of the rocking member itself. As a further alternative, the spring20 and the profile of the rocker I I may be retained, and the pivot I3may be given a truly radial movement either by a straight line motionlinkage, or by mounting it on a slide engaging with a slot formed in thebody of the dial.

In order to prevent noise and wear, we arrange to provide a disc 25 offelt, this disc being held against the impulse producing wheel I bymeans of a dished spring 26. This felt disc has a diameter slightlygreater than that of the root circle of the teeth, with the result thatthe spur of the rocker, in falling from the crests of the teeth,encounters a soft surface, this reducing noise. The disc is impregnatedwith a suitable lubricant, such as a thin oil, this reducing frictionalwear on the spur and teeth and helping to maintain the pivots of thedevice in a lubricated condition.

In order further to ensure freedom from wear in the remainder of themechanism of the dial, we provide a dust-excluding device, shown indetail in Figure 2. As is well known, a dial usually consists of a base21 containing the governor and gearing (not shown), these gears beingenclosed in a space covered by the number plate 28. As, however, thisplate does not make a very good joint either at its periphery or at theedge of the hole in its centre, we arrange a disc of felt 30 beneath theplate, this felt resting on a ledge 29 formed on the base of theinstrument. The number plate rests on this felt and is held in place bya wire ring 3| in known manner. In addition, a dust sealing device isalso employed to ensure that dust is excluded from the gap normallyexisting between the spindle of the dial and the inner edge ofthe holein the number plate through which the spindle passes. One or more discs33 are mounted on the central shaft 35 of the dial, these discs havingholes in their centres which are only very slightly greater than thediameter of the member 35. The outer edges of these discs are enclosedbetween further discs 34, these discs having holes in their centresappreciably larger than the diameter of the member 35 and overlappingthe edges of the hole formed in the plate 28. All these discs arepreferably made of some thin sheet material, such as that produciblefrom synthetic resin, and the outer discs 34 are fastened together andto the plate 28 by means of clips 36. These clips are made tight enoughto prevent rotation or the discs 34 relative to the finger plate, but donot prevent sliding of the discs 33 between the edges of the discs 34.Thus, during rotation of the dial, the central shaft 35 rotates in thediscs 33, the accurate fit of these discs round the shaft preventingingress of dust particles to a very considerable extent. Theconstruction of the device, however, is such that during assembly of thefinger plate, the discs 33 can slide transversely to a limited extentbetween the discs 34, this enabling them to locate themselves accuratelyaround the central shaft, whilst at the same time the finger plate canbe made an easy fit in the base 21.

As a still further precaution against wear a collar 39 of felt orsimilar material is provided on the pin I3 inside the pivoted end of therocking member II. This collar is impregnated with oil, and stands justproud of the centre of the cam-surface of the member II, this acting tolubricate the spring 20 and the cam surface. If desired, a similar feltcollar can be provided in connection with the bearing I4.

I claim:

1. An impulse sender having a finger plate and a toothed impulse sendingwheel connected thereto and rotated therewith, impulse producingcontacts, a pivoted rocker arm, a rocking member pivoted on said rockerarm so that the pivoted end of the member has radial movement relativeto said wheel, said member moved with its pivot point by forwardrotation of said wheel without operating said contacts and moved aboutits pivot point by the return of the wheel to operate said contacts.

2. An impulse sender as claimed in claim 1 having a pivoted arm havingsaid rocking member pivoted to the movable member of said arm so thatthe pivoted end of the member has movement about the pivot point of thearm.

3. An impulse sender as claimed in claim 1 in which the rotation of saidwheel causes rotary movement of the rocking member to a limited extentin the same direction as the teeth of the wheel, and also acorresponding reverse rotary movement of the member with the wheel toprovide lost motion of the member before the conshaped surface on thepivoted end of the arm,

and a spring engaging said surface and tending to hold the free end ofsaid arm always in engagement with the surface of said wheel.

5. An impulse sender as claimed in claim 4 in which said arm carries acollar of insulating material on its free end engaging the wheel, saidcollar removed from engagement with said contact springs on the forwardmovement of the wheel and engaged and operated by the teeth of the wheelon the back movement thereof to operate said springs.

6. In an impulse sender having a finger plate and a toothed impulsewheel rotated forward and backward thereby, impulse contacts, a pivotedarm, a rocking member'pivoted to the free end of said arm and having oneend engaging the surface of said wheel, said member and arm havingradial movement about the pivot point of said arm toward and away fromsaid wheel and movable backward and forward with the wheel in itsinitial forward and its initial backward movement, said member movedabout its pivot by said wheel on the latter part of its backwardmovement to engage and operate said contacts.

7. In an impulse sender as claimed in claim 6, having a spring engagingsaid member and acting thereon to hold the member in its extremeposition out of contact with said contacts and against said wheel onforward movement thereof, and against the wheel and in contact with thecontacts on the backward movement of the wheel.

8'. An impulse sender as claimed in claim 1 wherein said impulse wheelis provided with an oiled washer of porous material slightly larger thanthe root circle of the wheel and engaged by said rocking member.

9. An impulse sender having a finger hole dial and a toothed impulsewheel secured thereto and rotating therewith backward and forward,impulse springs, a rocker arm for controlling said springs pivoted on amovable member adjacent said wheels so that its pivot point has alimited radial movement relative said wheel, said rocker arm moved inone direction with the wheel on the forward movement thereof and back toits initial position on the first part of the backward movement thereof,said member on the remaining backward movement operated by the teeth ofsaid wheel in a movement to operate said springs intermittently.

10. An impulse sender as claimed in claim 1 having means for excludingdust from its interior comprising a series of thin disc washers closelymounted on the shaft of the finger wheel and other thin discs mounted inthe device on stationary parts thereof, the first disc slidable betweenthe other discs.

CHARLES CLARKE PUCKETTE.

